Large off-road machines are employed for moving large quantities of earth, such as in building highways or dams, and are used in hauling ore as a part of mining operations. These large machines are required to travel at fairly fast speeds for efficiency and economy of operation and normally travel on temporary road surfaces or over terrain on which work is being preformed. For this reason, these large off-road machines are somewhat dangerous to operate since conditions do not permit construction of smooth, level roadbeds in most work situations. With the heavy loads, at fairly fast speeds and uneven terrain, the possibility of rollover of large machines, while relatively infrequent, nevertheless, is a safety concern of manufacturers and users of such machines. For this reason, it is important to provide protection for an operator of such large off-road machines, and such protection is concentrated in the construction and the arrangement of the cab in which the driver controls the machine.
The Society Of Automotive Engineers has provided a design criteria entitled "Performance Criteria For Rollover Protection Structures (ROPS) For Construction, Earthmoving, Forestry, And Mining Machines--SAE J1040 APR88." The performance criteria sets out the suggested design requirements for the protection of a machine operator. Generally speaking, the design requirements relate to providing a superstructure cab housing having prescribed plastic deformation limits so that in the event of rollover, the cab superstructure will deform but not collapse. The plastic deformation of a frame superstructure is somewhat difficult to fully predict in advance. The present disclosure is directed toward a cab superstructure and the means for arranging the same to permit more predictable behavior of the cab superstructure in the event of rollover, with a higher confidence level in the design than is typically available.
When lateral force is applied to the rollover protective structure (ROPS), a force is introduced which must be absorbed either by plastic deformation or by some other method. The present disclosure improves the method of energy absorption thereby providing a safer environment for an operator.
For background information relating to rollover protection as suggested by others, reference may be had to the following U.S. Pat. Nos.: 13,600; 447,097; 1,312,422; 3,149,878; 3,612,581; 3,632,134; 3,868,190 and 3,866,942.